Where to buy cheapest dell laptops?

I want to buy a dell laptop for my birthday and was wondering where the cheapest place to buy them was. I live in the uk, so i need places that are here, or can ship here. I also need somewhere that does a good variety of colours. Links would be helpful.
Thanks a lot

Dell Inspiron 15R is a good value for the money, good procesor, good monitor, light for it’s dimensions. key are a bit too "plastic", noysee when you type, the case is a bit glossy, but the color is saving you from having a laptop full of fingertips.